Apparatus and method for transmitting and receiving transmission beam information and channel quality information in communication system supporting multi-user multi-input multi-output scheme

ABSTRACT

The present disclosure relates to a pre-5th-generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-generation (4G) communication system such as a long term evolution (LTE). A method for receiving transmission beam (Tx beam) information by a user equipment (UE) in a communication system supporting a multi-user multi-input multi-output (MU-MIMO) scheme is provided. The method includes transmitting information on a selected Tx beam to a base station (BS), and receiving Tx beam information including information for a Tx beam selected by at least one UE other than the UE from the BS.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 15/176,772, filed on Jun. 8, 2016, which claimed the benefit under35 U.S.C. §119(a) of a Korean patent application filed on Jun. 8, 2015in the Korean Intellectual Property Office and assigned Serial No.10-2015-0080610, the entire disclosure of which is hereby incorporatedby reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and method fortransmitting and receiving transmission beam (Tx beam) information andchannel quality information in a communication system supporting amulti-user multi-input multi-output (MU-MIMO) scheme. More particularly,the present disclosure relates to an apparatus and method fortransmitting and receiving Tx beam information and channel qualityinformation in a case that a millimeter wave (mmWave) beamforming schemeis used in a communication system supporting a MU-MIMO scheme.

BACKGROUND

To meet the demand for wireless data traffic, which has increased sincedeployment of 4th-generation (4G) communication systems, efforts havebeen made to develop an improved 5th-generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘beyond 4G network’ or a ‘post long-term evolution(LTE) system’.

It is considered that the 5G communication system will be implemented inmillimeter wave (mmWave) bands, e.g., 60 GHz bands, so as to accomplishhigher data rates. To reduce propagation loss of radio waves andincrease a transmission distance, a beam forming technique, a massivemultiple-input multiple-output (MIMO) technique, a full dimensional MIMO(FD-MIMO) technique, an array antenna technique, an analog beam formingtechnique, and a large scale antenna technique are discussed in 5Gcommunication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, a device-to-device (D2D)communication, a wireless backhaul, a moving network, a cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation, and the like.

In the 5G system, a hybrid frequency shift keying (FSK) and quadratureamplitude modulation (QAM) modulation (FQAM) and a sliding windowsuperposition coding (SWSC) as an advanced coding and modulation (ACM)scheme, and a filter bank multi carrier (FBMC) scheme, a non-orthogonalmultiple Access (NOMA) scheme, and a sparse code multiple access (SCMA)scheme as an advanced access technology have been developed.

In a communication system supporting a multi-user MIMO (MU-MIMO) scheme,each user equipment (UE) feeds back channel quality information based ona channel status between each UE and a base station (BS) forcommunication with the BS. For example, the channel quality informationmay be a channel quality index (CQI).

The BS determines a modulation and coding scheme (MCS) level for each UEbased on the channel quality information fed back by each UE, andtransmits data to each UE based on the MCS level.

Recently, in broadband carrier transmission using a mmWave band whichhas emerged as 5G communication, an array antenna is used as eachtransmission antenna (Tx antenna), so a beam gain may be acquired basedon radio frequency (RF) beamforming. In this case, a UE performs a beamsweeping process for each Tx antenna, and selects an optimal Tx antennaand an optimal transmission beam (Tx beam) based on a result of the beamsweeping process.

In a communication system supporting a single-user MIMO (SU-MIMO)scheme, a UE knows a beam index for each of a plurality of Tx antennasincluded in a BS, so the UE may determine a CQI based on the beam indexfor each of the plurality of Tx antennas.

Alternatively, in a communication system supporting a MU-MIMO scheme,each UE knows only a beam index for a Tx antenna allocated to each UEamong a plurality of Tx antennas included in a BS and does not know beamindexes for Tx antennas allocated to other UEs. Each UE does not knowbeam indexes for Tx antennas allocated to other UEs, so each UE may notdetect interference due to beams for the Tx antennas allocated to theother UEs and determine a correct CQI.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide an apparatus and method for transmitting andreceiving Tx beam information in a communication system supporting amulti-user multi-input multi-output (MU-MIMO) scheme.

Another aspect of the present disclosure is to provide an apparatus andmethod for transmitting and receiving Tx beam information in a case thata mmWave beamforming scheme is used in a communication system supportinga MU-MIMO scheme.

Another aspect of the present disclosure is to provide an apparatus andmethod for transmitting and receiving channel quality information in acommunication system supporting a MU-MIMO scheme.

Another aspect of the present disclosure is to provide an apparatus andmethod for transmitting and receiving channel quality information in acase that a mmWave scheme is used in a communication system supporting aMU-MIMO scheme.

Another aspect of the present disclosure is to provide an apparatus andmethod for generating channel quality information by consideringinterference strength in a case that a mmWave scheme is used in acommunication system supporting a MU-MIMO scheme.

Another aspect of the present disclosure is to provide an apparatus andmethod for generating channel quality information based on Tx beaminformation for UEs other than a UE in a communication system supportinga MU-MIMO scheme.

In accordance with an aspect of the present disclosure, a method forreceiving transmission beam (Tx beam) information by a user equipment(UE) in a communication system supporting a MU-MIMO scheme is provided.The method includes transmitting information on a selected Tx beam to abase station (BS), and receiving Tx beam information includinginformation for a Tx beam selected by at least one UE other than the UEfrom the BS.

In accordance with another aspect of the present disclosure, a methodfor transmitting Tx beam information by a BS in a communication systemsupporting a MU-MIMO scheme is provided. The method includes receivingTx beam information on a Tx beam selected by a first UE from the firstUE, and transmitting the received Tx beam information to at least onesecond UE.

In accordance with another aspect of the present disclosure, a UE in acommunication system supporting a MU-MIMO scheme is provided. The UEincludes a transmitter configured to transmit information on a selectedTx beam to a BS, and a receiver configured to receive Tx beaminformation including information for a Tx beam selected by at least oneUE other than the UE from the BS.

In accordance with another aspect of the present disclosure, a BS in acommunication system supporting a MU-MIMO scheme is provided. The BSincludes a receiver configured to receive Tx beam information on a Txbeam selected by a UE from the UE, and a transmitter configured totransmit the Tx beam information to at least one UE other than the UE.

In accordance with another aspect of the present disclosure, anon-transitory computer-readable storage medium is provided. Thenon-transitory computer-readable storage medium stores instructionsthat, when executed, cause at least one processor of a user equipment(UE) in a communication system supporting a multi-user multi-inputmulti-output (MU-MIMO) scheme to perform a method, the methodcomprising: transmitting information on a selected Tx beam to a basestation (BS); and receiving Tx beam information including informationfor a Tx beam selected by at least one UE other than the UE from the BS.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 schematically illustrates an example of a cross-forwardingprocess in a case that a millimeter Wave (mmWave) beamforming scheme isused in a communication system supporting a multi-user multi-inputmulti-output (MU-MIMO) scheme according to an embodiment of the presentdisclosure;

FIG. 2 schematically illustrates another example of a cross-forwardingprocess in a case that a mmWave beamforming scheme is used in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure;

FIG. 3 schematically illustrates still another example of across-forwarding process in a case that a mmWave beamforming scheme isused in a communication system supporting a MU-MIMO scheme according toan embodiment of the present disclosure;

FIG. 4 schematically illustrates an example of an operating process of abase station (BS) in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure;

FIG. 5 schematically illustrates an example of an operating process of auser equipment (UE) in a communication system supporting a MU-MIMOscheme according to an embodiment of the present disclosure;

FIG. 6 schematically illustrates another example of an operating processof a BS in a communication system supporting a MU-MIMO scheme accordingto an embodiment of the present disclosure;

FIG. 7 schematically illustrates another example of an operating processof a UE in a communication system supporting a MU-MIMO scheme accordingto an embodiment of the present disclosure;

FIG. 8 schematically illustrates still another example of an operatingprocess of a BS in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure;

FIG. 9 schematically illustrates still another example of an operatingprocess of a UE in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure;

FIG. 10 schematically illustrates an inner structure of a BS in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure; and

FIG. 11 schematically illustrates an inner structure of a UE in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Although ordinal numbers such as “first,” “second,” and so forth will beused to describe various components, those components are not limitedherein. The terms are used only for distinguishing one component fromanother component. For example, a first component may be referred to asa second component and likewise, a second component may also be referredto as a first component, without departing from the teaching of theinventive concept. The term “and/or” used herein includes any and allcombinations of one or more of the associated listed items.

It will be further understood that the terms “comprises” and/or “has,”when used in this specification, specify the presence of a statedfeature, number, step, operation, component, element, or combinationthereof, but do not preclude the presence or addition of one or moreother features, numbers, steps, operations, components, elements, orcombinations thereof.

The terms used herein, including technical and scientific terms, havethe same meanings as terms that are generally understood by thoseskilled in the art, as long as the terms are not differently defined. Itshould be understood that terms defined in a generally-used dictionaryhave meanings coinciding with those of terms in the related technology.

According to various embodiments of the present disclosure, anelectronic device may include communication functionality. For example,an electronic device may be a smart phone, a tablet personal computer(PC), a mobile phone, a video phone, an e-book reader, a desktop PC, alaptop PC, a netbook PC, a personal digital assistant (PDA), a portablemultimedia player (PMP), an mp3 player, a mobile medical device, acamera, a wearable device (e.g., a head-mounted device (HMD), electronicclothes, electronic braces, an electronic necklace, an electronicappcessory, an electronic tattoo, or a smart watch), and/or the like.

According to various embodiments of the present disclosure, anelectronic device may be a smart home appliance with communicationfunctionality. A smart home appliance may be, for example, a television(TV), a digital versatile disc (DVD) player, an audio, a refrigerator,an air conditioner, a vacuum cleaner, an oven, a microwave oven, awasher, a dryer, an air purifier, a set-top box, a TV box (e.g., SamsungHomeSync™, Apple TV™, or Google TV™), a gaming console, an electronicdictionary, an electronic key, a camcorder, an electronic picture frame,and/or the like.

According to various embodiments of the present disclosure, anelectronic device may be a medical device (e.g., magnetic resonanceangiography (MRA) device, a magnetic resonance imaging (MRI) device,computed tomography (CT) device, an imaging device, or an ultrasonicdevice), a navigation device, a global positioning system (GPS)receiver, an event data recorder (EDR), a flight data recorder (FDR), anautomotive infotainment device, a naval electronic device (e.g., navalnavigation device, gyroscope, or compass), an avionic electronic device,a security device, an industrial or consumer robot, and/or the like.

According to various embodiments of the present disclosure, anelectronic device may be furniture, part of a building/structure, anelectronic board, electronic signature receiving device, a projector,various measuring devices (e.g., water, electricity, gas orelectro-magnetic wave measuring devices), and/or the like that includecommunication functionality.

According to various embodiments of the present disclosure, anelectronic device may be any combination of the foregoing devices. Inaddition, it will be apparent to one having ordinary skill in the artthat an electronic device according to various embodiments of thepresent disclosure is not limited to the foregoing devices.

According to various embodiments of the present disclosure, for example,a user equipment (UE) may be an electronic device.

According to various embodiments of the present disclosure, a signaltransmitting apparatus may be a UE or a base station (BS).

According to various embodiments of the present disclosure, a signalreceiving apparatus may be a UE or a BS.

According to various embodiments of the present disclosure, a signaltransmitting/receiving apparatus may be a UE or a BS.

In various embodiments of the present disclosure, the term UE may beinterchangeable with the term mobile station (MS), wireless terminal,mobile device, and the like.

In various embodiments of the present disclosure, the term BS may beinterchangeable with the term node B, evolved node B (eNB), access point(AP), and the like.

In various embodiments of the present disclosure, the term “transmit”may be interchangeable with the term “feed back”, “feed forward”, andthe like.

An embodiment of the present disclosure proposes an apparatus and methodfor transmitting and receiving transmission beam (Tx beam) informationin a communication system supporting a multi-user multi-inputmulti-output (MU-MIMO) scheme.

An embodiment of the present disclosure proposes an apparatus and methodfor transmitting and receiving Tx beam information in a case that amillimeter Wave (mmWave) beamforming scheme is used in a communicationsystem supporting a MU-MIMO scheme.

An embodiment of the present disclosure proposes an apparatus and methodfor transmitting and receiving channel quality information in acommunication system supporting a MU-MIMO scheme.

An embodiment of the present disclosure proposes an apparatus and methodfor transmitting and receiving channel quality information in a casethat a mmWave scheme is used in a communication system supporting aMU-MIMO scheme.

An embodiment of the present disclosure proposes an apparatus and methodfor generating channel quality information by considering interferencestrength in a case that a mmWave scheme is used in a communicationsystem supporting a MU-MIMO scheme.

An embodiment of the present disclosure proposes an apparatus and methodfor generating channel quality information based on Tx beam informationfor UEs other than a UE in a communication system supporting a MU-MIMOscheme.

An apparatus and method proposed in an embodiment of the presentdisclosure may be applied to various communication systems such as along term evolution (LTE) mobile communication system, an LTE-advanced(LTE-A) mobile communication system, a licensed-assisted access(LAA)-LTE mobile communication system, a high speed downlink packetaccess (HSDPA) mobile communication system, a high speed uplink packetaccess (HSUPA) mobile communication system, a high rate packet data(HRPD) mobile communication system proposed in a 3rd generationpartnership project 2 (3GPP2), a wideband code division multiple access(WCDMA) mobile communication system proposed in the 3GPP2, a codedivision multiple access (CDMA) mobile communication system proposed inthe 3GPP2, an institute of electrical and electronics engineers (IEEE)802.16m communication system, an IEEE 802.16e communication system, anevolved packet system (EPS), and a mobile internet protocol (Mobile IP)system, a digital video broadcast system such as a mobile broadcastservice such as a digital multimedia broadcasting (DMB) service, adigital video broadcasting-handheld (DVP-H), an advanced televisionsystems committee-mobile/handheld (ATSC-M/H) service, and the like, andan internet protocol television (IPTV), a moving picture experts group(MPEG) media transport (MMT) system and/or the like.

In an embodiment of the present disclosure, for example, Tx beaminformation may be a Tx beam index.

In an embodiment of the present disclosure, for example, channel qualityinformation may be a channel quality index (CQI).

In an embodiment of the present disclosure, a UE corrects a signal tointerference and noise ratio (SINR) based on received signal strengthper Tx beam measured upon performing a beam sweeping process fordetecting an optimal transmission antenna (Tx antenna) and an optimal Txbeam, and determines a CQI based on the corrected SINR.

In an embodiment of the present disclosure, it will be assumed that anSINR is used as an example of information indicating channel status.However, various metrics such as received signal code power (RSCP),reference signal received power (RSRP), a reference signal strengthindicator (RSSI), reference signal received quality (RSRQ), acarrier-to-interference noise ratio (CINR), a signal-to-noise ratio(SNR), a block error rate (BLER), and/or the like may be used as theinformation indicating the channel status.

That is, a received signal strength for each of beams applied to aplurality of Tx antennas included in a BS which is measured by a UEbecomes interference strength for UEs other than the UE if acorresponding beam is used for the other UEs.

Therefore, a UE may detect interference strength if the UE knows Tx beamindexes allocated to UEs other than the UE.

An effective SINR for determining CQI may be expressed as Equation 1.

$\begin{matrix}{\gamma_{eff} = \frac{P_{S}}{P_{I} + P_{N}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, γ_(eff) denotes an effective SINR, P_(S) denotes signalstrength, P_(I) denotes interference strength, and P_(N) denotes noisestrength.

The UE may measure P_(N) if there is no signal transmitted from a signaltransmitting apparatus, e.g., a BS to the UE. The UE may measure P_(S)and P_(I) while performing a beam sweeping process.

Therefore, in a case that a UE may know Tx beam indexes allocated to UEsother than the UE, the UE may substitute P_(I) which corresponds to Txbeam indexes allocated to the UEs to an equation for determining aneffective SINR expressed in Equation 1. In this case, the effective SINRmay be determined based on correct P_(I), so the CQI determined based onthe effective SINR also becomes correct.

In a case that a mmWave beamforming scheme is used in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure, a beam sweeping process needs to be performed forbeams of various directions for detecting an optimal Tx antenna and anoptimal Tx beam.

In an embodiment of the present disclosure, a detailed description of abeam sweeping process will be omitted, and a cross-forwarding processfor an optimal Tx beam pattern index selected through the beam sweepingprocess will be described below.

An example of a cross-forwarding process in a case that a mmWavebeamforming scheme is used in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure willbe described with reference to FIG. 1.

FIG. 1 schematically illustrates an example of a cross-forwardingprocess in a case that a mmWave beamforming scheme is used in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 1, a communication system supporting a MU-MIMO schemeincludes a BS 110, and a plurality of UEs, e.g., N UEs, e.g., two UEs,e.g., a UE#1 120 and a UE#2 130. The BS 110 includes a plurality of Txantennas, e.g., M Tx antennas, e.g., two Tx antennas, e.g., a Txantenna#1 111-1 and a Tx antenna#2 111-2.

In a case that a mmWave beamforming scheme is used in a signaltransmitting apparatus or a signal transmitting/receiving apparatus, abeam sweeping process is performed for Tx beams of various directions asillustrated in FIG. 1 for detecting an optimal TX antenna and an optimalTx beam.

It will be assumed that the UE#1 120 receives data corresponding to oneof Tx beam patterns provided in the Tx antennal#1 111-1, and the UE#2130 receives data corresponding to one of Tx beam patterns provided inthe Tx antennal#2 111-2, according to the beam sweeping process. In thiscase, the Tx beam patterns provided in the Tx antennal#1 111-1 act asinterference for the UE#2 130 (140), and the Tx beam patterns providedin the Tx antennal#2 111-2 act as interference for the UE#1 120 (150).

The UE#1 120 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#1 111-1, that is, the UE#1 120selects the Tx antenna#1 111-1 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#1 111-1 as an optimalTx beam. Therefore, the UE#1 120 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#1 111-1 (160). The feedback information transmitted fromthe UE#1 120 to the BS 110 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#1 111-1, e.g., a Txbeam index 1 (TxBI1).

The UE#2 130 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#2 111-2, that is, the UE#2 130selects the Tx antenna#2 111-2 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#2 111-2 as an optimalTx beam. Therefore, the UE#2 130 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#2 111-2 (170). The feedback information transmitted fromthe UE#2 130 to the BS 110 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#2 111-2, e.g., a Txbeam index 2 (TxBI2).

As described in Equation 1, an effective SINR required for a UE todetermine a CQI may be detected correctly if the UE knows interferencestrength correctly. Therefore, in an embodiment of the presentdisclosure, a BS transmits an optimal Tx beam pattern index included infeedback information received from a specific UE to remaining UEs exceptfor the specific UE.

For example, in FIG. 1, the BS 110 feeds forward the optimal Tx beampattern index received from the UE#1 120 to remaining UEs except for theUE#1 120 among UEs to which the BS 110 provides a service, e.g., theUE#2 130 (180).

After receiving the optimal Tx beam pattern index that the BS 110receives from the UE#1 120 from the BS 110, the UE#2 130 determines aneffective SINR as described in Equation 1 by setting strength whichcorresponds to the optimal Tx beam pattern index received from the UE#1120, i.e., TxBI1 as interference strength PI.

For example, in FIG. 1, the BS 110 feeds forward the optimal Tx beampattern received from the UE#2 130 to remaining UEs except for the UE#2130 among UEs to which the BS 110 provides a service, e.g., the UE#1 120(190).

After receiving the optimal Tx beam pattern index that the BS 110receives from the UE#2 130 from the BS 110, the UE#1 120 determines aneffective SINR as described in Equation 1 by setting strength whichcorresponds to the optimal Tx beam pattern index received from the UE#2130, e.g., TxBI2 as interference strength PI.

In an embodiment of the present disclosure, it will be assumed that atiming point at which an optimal Tx beam pattern index is transmitted isidentical to a timing point at which a UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmitted at atiming point different from a timing point at which the CQI istransmitted. A detailed description of the timing point at which the CQIis transmitted will be omitted herein.

In an embodiment of the present disclosure, it will be assumed that amessage with which a UE transmits an optimal Tx beam pattern index isidentical to a message with which the UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmittedthrough a message different from the message through which the CQI istransmitted. A detailed description of the message used for transmittingthe optimal Tx beam pattern index will be omitted herein.

In an embodiment of the present disclosure, a period by which a CQI andan optimal Tx beam pattern index are transmitted may be variable. In anembodiment of the present disclosure, the period by which the CQI andthe optimal Tx beam pattern index are transmitted may be determined as aperiod during which channel status is static.

For convenience, a process in which a BS transmits a Tx beam patternindex received from a UE to UEs other than the UE as described abovewill be referred to as “cross-forwarding process”. By means of thecross-forwarding process, a UE may know optimal Tx beam indexes for UEsother than the UE, and detect a strength of a signal which correspondsto the optimal Tx beam indexes for the UEs other than the UE asinterference strength. The UE may detect interference strengthcorrectly, so the UE may detect an effective SINR correctly and detect aCQI correctly.

An example of a cross-forwarding process in a case that a mmWavebeamforming scheme is used in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure hasbeen described with reference to FIG. 1, and another example of across-forwarding process in a case that a mmWave beamforming scheme isused in a communication system supporting a MU-MIMO scheme according toan embodiment of the present disclosure will be described with referenceto FIG. 2.

FIG. 2 schematically illustrates another example of a cross-forwardingprocess in a case that a mmWave beamforming scheme is used in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 2, a communication system supporting a MU-MIMO schemeincludes a BS 210, and a plurality of UEs, e.g., N UEs, e.g., two UEs,e.g., a UE#1 220 and a UE#2 230. The BS 210 includes a plurality of Txantennas, e.g., M Tx antennas, e.g., two Tx antennas, e.g., a Txantenna#1 211-1 and a Tx antenna#2 211-2.

In a case that a mmWave beamforming scheme is used in a signaltransmitting apparatus or a signal transmitting/receiving apparatus, abeam sweeping process is performed for Tx beams of various directions asillustrated in FIG. 2 for detecting an optimal TX antenna and an optimalTx beam.

It will be assumed that the UE#1 220 receives data corresponding to oneof Tx beam patterns provided in the Tx antennal#2 211-2, and the UE#2230 receives data corresponding to one of Tx beam patterns provided inthe Tx antennal#1 211-1, according to the beam sweeping process. In thiscase, the Tx beam patterns provided in the Tx antennal#1 211-1 act asinterference for the UE#1 220 (240), and the Tx beam patterns providedin the Tx antennal#2 111-2 act as interference for the UE#2 230 (250).

The UE#1 220 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#2 211-2, that is, the UE#1 220selects the Tx antenna#2 211-2 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#2 211-2 as an optimalTx beam. Therefore, the UE#1 220 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#2 211-2 (260). The feedback information transmitted fromthe UE#1 220 to the BS 210 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#2 211-2, e.g., TxBI2.

The UE#2 230 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#1 211-1, that is, the UE#2 230selects the Tx antenna#1 211-1 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#1 211-1 as an optimalTx beam. Therefore, the UE#2 230 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#1 211-1 (270). The feedback information transmitted fromthe UE#2 230 to the BS 210 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#1 211-1, e.g., TxBI1.

As described in Equation 1, an effective SINR required for a UE todetermine a CQI may be detected correctly if the UE knows interferencestrength correctly. Therefore, in an embodiment of the presentdisclosure, a BS transmits an optimal Tx beam pattern index included infeedback information received from a UE to remaining UEs except for theUE.

For example, in FIG. 2, the BS 210 feeds forward the optimal Tx beampattern index received from the UE#1 220 to remaining UEs except for theUE#1 220 among UEs to which the BS 210 provides a service, e.g., theUE#2 230 (280).

After receiving the optimal Tx beam pattern index that the BS 210receives from the UE#1 220 from the BS 210, the UE#2 230 determines aneffective SINR as described in Equation 1 by setting strength whichcorresponds to the optimal Tx beam pattern index received from the UE#1220, i.e., TxBI2 as interference strength PI.

For example, in FIG. 2, the BS 210 feeds forward the optimal Tx beampattern received from the UE#2 230 to remaining UEs except for the UE#2230 among UEs to which the BS 210 provides a service, e.g., the UE#1 220(290).

After receiving the optimal Tx beam pattern index that the BS 210receives from the UE#2 230 from the BS 210, the UE#1 220 determines aneffective SINR as described in Equation 1 by setting strength whichcorresponds to the optimal Tx beam pattern index received from the UE#2130, e.g., TxBI1 as interference strength PI.

In an embodiment of the present disclosure, it will be assumed that atiming point at which an optimal Tx beam pattern index is transmitted isidentical to a timing point at which a UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmitted at atiming point different from a timing point at which the CQI istransmitted. A detailed description of the timing point at which the CQIis transmitted will be omitted herein.

In an embodiment of the present disclosure, it will be assumed that amessage through which a UE transmits an optimal Tx beam pattern index isidentical to a message through which the UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmittedthrough a message different from the message through which the CQI istransmitted. A detailed description of the message used for transmittingthe optimal Tx beam pattern index will be omitted herein.

In an embodiment of the present disclosure, a period by which a CQI andan optimal Tx beam pattern index are transmitted may be variable. In anembodiment of the present disclosure, the period by which the CQI andthe optimal Tx beam pattern index are transmitted may be determined as aperiod during which channel status is static.

By means of the cross-forwarding process, a UE may know optimal Tx beamindexes for UEs other than the UE, and detect strength of a signal whichcorresponds to the optimal Tx beam indexes for the UEs other than the UEas interference strength. The UE may detect interference strengthcorrectly, so the UE may detect an effective SINR correctly and detect aCQI correctly.

Another example of a cross-forwarding process in a case that a mmWavebeamforming scheme is used in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure hasbeen described with reference to FIG. 2, and still another example of across-forwarding process in a case that a mmWave beamforming scheme isused in a communication system supporting a MU-MIMO scheme according toan embodiment of the present disclosure will be described with referenceto FIG. 3.

FIG. 3 schematically illustrates still another example of across-forwarding process in a case that a mmWave beamforming scheme isused in a communication system supporting a MU-MIMO scheme according toan embodiment of the present disclosure.

Referring to FIG. 3, a communication system supporting a MU-MIMO schemeincludes a BS 310, and a plurality of UEs, e.g., N UEs, e.g., four UEs,e.g., a UE#1 320, a UE#2 330, a UE#3 340, and a UE#4 350. The BS 310includes a plurality of Tx antennas, e.g., M Tx antennas, e.g., four Txantennas, e.g., a Tx antenna#1 311-1, a Tx antenna#2 311-2, a Txantenna#3 311-3, and a Tx antenna#4 311-4.

In a case that a mmWave beamforming scheme is used in a signaltransmitting apparatus or a signal transmitting/receiving apparatus, abeam sweeping process is performed for Tx beams of various directions asillustrated in FIG. 3 for detecting an optimal TX antenna and an optimalTx beam.

It will be assumed that the UE#1 320 receives data corresponding to oneof Tx beam patterns provided in the Tx antennal#1 311-1, the UE#2 330receives data corresponding to one of Tx beam patterns provided in theTx antennal#2 311-2, the UE#3 340 receives data corresponding to one ofTx beam patterns provided in the Tx antennal#3 311-3, and the UE#4 350receives data corresponding to one of Tx beam patterns provided in theTx antennal#4 311-4, according to the beam sweeping process.

In this case, the Tx beam patterns provided in the Tx antennal#1 311-1act as interference for each of the UE#2 330, the UE#3 340, and the UE#4350 (325-1, 325-2, 325-3), the Tx beam patterns provided in the Txantennal#2 311-2 act as interference for each of the UE#1 320, the UE#3340, and the UE#4 350 (335-1, 335-2, 335-3), the Tx beam patternsprovided in the Tx antennal#3 311-3 act as interference for each of theUE#1 320, the UE#2 330, and the UE#4 350 (345-1, 345-2, 345-3), and theTx beam patterns provided in the Tx antennal#4 311-4 act as interferencefor each of the UE#1 320, the UE#2 330, and the UE#3 340 (355-1, 355-2,355-3).

The UE#1 320 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#1 311-1, that is, the UE#1 320selects the Tx antenna#1 311-1 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#1 311-1 as an optimalTx beam. Therefore, the UE#1 320 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#1 311-1 (321). The feedback information transmitted fromthe UE#1 320 to the BS 310 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#1 311-1, e.g., TxBI1.

The UE#2 330 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#2 311-2, that is, the UE#2 330selects the Tx antenna#2 311-2 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#2 311-2 as an optimalTx beam. Therefore, the UE#2 330 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#2 311-2 (331). The feedback information transmitted fromthe UE#2 330 to the BS 310 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#2 311-2, e.g., TxBI2.

The UE#3 340 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#3 311-3, that is, the UE#3 340selects the Tx antenna#3 311-3 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#3 311-3 as an optimalTx beam. Therefore, the UE#3 340 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#3 311-3 (341). The feedback information transmitted fromthe UE#3 340 to the BS 310 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#3 311-3, e.g., TxBI3.

The UE#4 350 determines to receive data corresponding to one of the Txbeam patterns provided in the Tx antenna#4 311-4, that is, the UE#4 350selects the Tx antenna#4 311-4 as an optimal Tx antenna, and selects oneof the Tx beam patterns provided in the Tx antenna#4 311-4 as an optimalTx beam. Therefore, the UE#4 350 transmits feedback information that theoptimal Tx beam pattern is set as one of Tx beam patterns provided inthe Tx antenna#4 311-4 (351). The feedback information transmitted fromthe UE#4 350 to the BS 310 includes an optimal Tx beam pattern index,and it will be assumed that the optimal Tx beam pattern index is one ofTx beam pattern indexes provided in the Tx antenna#4 311-4, e.g., TxBI4.

As described in Equation 1, an effective SINR required for a UE todetermine a CQI may be detected correctly if the UE knows interferencestrength correctly. Therefore, in an embodiment of the presentdisclosure, a BS transmits an optimal Tx beam pattern index included infeedback information received from a UE to remaining UEs except for theUE.

For example, in FIG. 3, the BS 310 feeds forward the optimal Tx beampattern index received from the UE#1 320 to remaining UEs except for theUE#1 320 among UEs to which the BS 310 provides a service, e.g., theUE#2 330, the UE#3 340, and the UE#4 350 (333, 343, 353).

The BS 310 feeds forward the optimal Tx beam pattern index received fromthe UE#2 330 to remaining UEs except for the UE#2 330 among UEs to whichthe BS 310 provides a service, e.g., the UE#1 320, the UE#3 340, and theUE#4 350 (323, 343, 353).

The BS 310 feeds forward the optimal Tx beam pattern index received fromthe UE#3 340 to remaining UEs except for the UE#3 340 among UEs to whichthe BS 310 provides a service, e.g., the UE#1 320, the UE#2 330, and theUE#4 350 (323, 333, 353).

The BS 310 feeds forward the optimal Tx beam pattern index received fromthe UE#4 350 to remaining UEs except for the UE#4 350 among UEs to whichthe BS 310 provides a service, e.g., the UE#1 320, the UE#2 330, and theUE#3 340 (323, 333, 343).

As a result, the BS 310 transmits an optimal Tx beam index received fromeach of the UE#2 330, the UE#3 340, and the UE#4 350, i.e., TxBI2,TxBI3, and TxBI4 to the UE#1 320 (323).

The BS 310 transmits an optimal Tx beam index received from each of theUE#1 320, the UE#3 340, and the UE#4 350, i.e., TxBI1, TxBI3, and TxBI4to the UE#2 330 (333).

The BS 310 transmits an optimal Tx beam index received from each of theUE#1 320, the UE#2 330, and the UE#4 350, i.e., TxBI1, TxBI2, and TxBI4to the UE#3 340 (343).

The BS 310 transmits an optimal Tx beam index received from each of theUE#1 320, the UE#2 330, and the UE#3 340, i.e., TxBI1, TxBI2, and TxBI3to the UE#4 350 (353).

After receiving the optimal Tx beam pattern index that the BS 310receives from each of the UE#2 330, the UE#3 340, and the UE#4 350 fromthe BS 310, the UE#1 320 determines an effective SINR as described inEquation 1 by setting strength which corresponds to the optimal Tx beampattern indexes received from the UE#2 330, the UE#3 340, and the UE#4350, i.e., TxBI2, TxBI3, and TxBI4 as interference strength PI.

After receiving the optimal Tx beam pattern index that the BS 310receives from each of the UE#1 320, the UE#3 340, and the UE#4 350 fromthe BS 310, the UE#2 330 determines an effective SINR as described inEquation 1 by setting strength which corresponds to the optimal Tx beampattern indexes received from the UE#1 320, the UE#3 340, and the UE#4350, i.e., TxBI1, TxBI3, and TxBI4 as interference strength PI.

After receiving the optimal Tx beam pattern index that the BS 310receives from each of the UE#1 320, the UE#2 330, and the UE#4 350 fromthe BS 310, the UE#3 340 determines an effective SINR as described inEquation 1 by setting strength which corresponds to the optimal Tx beampattern indexes received from the UE#1 320, the UE#2 330, and the UE#4350, i.e., TxBI1, TxBI2, and TxBI4 as interference strength PI.

After receiving the optimal Tx beam pattern index that the BS 310receives from each of the UE#1 320, the UE#2 330, and the UE#3 340 fromthe BS 310, the UE#4 350 determines an effective SINR as described inEquation 1 by setting strength which corresponds to the optimal Tx beampattern indexes received from the UE#1 320, the UE#2 330, and the UE#3340, i.e., TxBI1, TxBI2, and TxBI3 as interference strength PI.

In an embodiment of the present disclosure, it will be assumed that atiming point at which an optimal Tx beam pattern index is transmitted isidentical to a timing point at which a UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmitted at atiming point different from a timing point at which the CQI istransmitted. A detailed description of the timing point at which the CQIis transmitted will be omitted herein.

In an embodiment of the present disclosure, it will be assumed that amessage with which a UE transmits an optimal Tx beam pattern index isidentical to a message with which the UE transmits a CQI.

Alternatively, the optimal Tx beam pattern index may be transmittedthrough a message different from the message through which the CQI istransmitted. A detailed description of the message used for transmittingthe optimal Tx beam pattern index will be omitted herein.

In an embodiment of the present disclosure, a period by which a CQI andan optimal Tx beam pattern index are transmitted may be variable. In anembodiment of the present disclosure, the period by which the CQI andthe optimal Tx beam pattern index are transmitted may be determined as aperiod during which channel status is static.

By means of the cross-forwarding process, a UE may know optimal Tx beamindexes for UEs other than the UE, and detect strength of a signal whichcorresponds to the optimal Tx beam indexes for the UEs as interferencestrength. The UE may detect interference strength correctly, so the UEmay detect an effective SINR correctly and detect a CQI correctly.

Still another example of a cross-forwarding process in a case that ammWave beamforming scheme is used in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure hasbeen described with reference to FIG. 3, and an example of an operatingprocess of a BS in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure will be describedwith reference to FIG. 4.

FIG. 4 schematically illustrates an example of an operating process of aBS in a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 4, for example, it will be assumed that an operatingprocess of a BS in FIG. 4 is an operating process of a BS according to across-forwarding process described in FIG. 1. That is, it will beassumed that an operating process of a BS in FIG. 4 is an operatingprocess of a BS according to a cross-forwarding process in a case that aBS uses two Tx antennas, e.g., a Tx antenna#1 and a Tx antenna#2 andprovides a service to two UEs, e.g., a UE#1 and a UE#2.

A BS transmits a signal to a UE#1 corresponding to a preset optimal Txbeam index at a preset timing point T1 and transmits a signal to a UE#2corresponding to a preset optimal Tx beam index at the timing point T1at operation 411. For example, the timing point T1 may be a schedulingtiming point.

The BS receives an optimal Tx beam index from each of the UE#1 and theUE#2 at operation 413. Here, it will be assumed that the UE#1 fed backTxBI1 as an optimal Tx beam index and the UE#2 fed back TxBI2 as anoptimal Tx beam index.

The BS feeds forward the optimal Tx beam index TxBI1 received from theUE#1 to the UE#2 thereby the UE#2 detects a correct effective SINR tofeed back a correct CQI to the BS at operation 415. Further, the BSfeeds forward the optimal Tx beam index TxBI2 received from the UE#2 tothe UE#1 thereby the UE#1 detects a correct effective SINR to feed backa correct CQI to the BS at operation 415.

The BS receives a CQI from each of the UE#1 and the UE#2 at operation417. The CQI received from the UE1 is a CQI that the UE#1 determines byconsidering interference strength for remaining UEs other than the UE#1correctly, and the CQI received from the UE2 is a CQI that the UE#2determines by considering interference strength for remaining UEs otherthan the UE#2 correctly.

Although FIG. 4 illustrates an example of an operating process of a BSin a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure, various changes could be made toFIG. 4. For example, although shown as a series of operations, variousoperations in FIG. 4 could overlap, occur in parallel, occur in adifferent order, or occur multiple times.

An example of an operating process of a BS in a communication systemsupporting a MU-MIMO scheme according to an embodiment of the presentdisclosure has been described with reference to FIG. 4, and an exampleof an operating process of a UE in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure willbe described with reference to FIG. 5.

FIG. 5 schematically illustrates an example of an operating process of aUE in a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 5, for example, it will be assumed that an operatingprocess of a UE in FIG. 5 is an operating process of a UE according to across-forwarding process described in FIG. 1. That is, it will beassumed that an operating process of a UE in FIG. 5 is an operatingprocess of a UE#1 according to a cross-forwarding process in a case thata BS uses two Tx antennas, e.g., a Tx antenna#1 and a Tx antenna#2 andprovides a service to two UEs, e.g., the UE#1 and a UE#2.

The UE#1 receives a signal from a BS at a preset timing point T1 atoperation 511. The UE#1 performs a beam sweeping process on the signalreceived from the BS to detect an optimal Tx beam pattern index atoperation 513. Here, it will be assumed that the UE#1 detects TxBI1 asan optimal Tx beam pattern index.

The UE#1 feeds back the detected optimal Tx beam pattern index TxBI1 tothe BS at operation 515. The UE#1 receives an optimal Tx beam patternindex transmitted by a remaining UE other than the UE#1, e.g., the UE#2from the BS at operation 517.

The UE#1 detects a correct effective SINR by detecting interferencestrength PI based on the optimal Tx beam pattern index transmitted bythe UE#2 which is received from the BS and determines a correct CQIbased on the correct effective SINR at operation 519.

The UE#1 feeds back the determined CQI to the BS at operation 521.

Although FIG. 5 illustrates an example of an operating process of a UEin a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure, various changes could be made toFIG. 5. For example, although shown as a series of operations, variousoperations in FIG. 5 could overlap, occur in parallel, occur in adifferent order, or occur multiple times.

An example of an operating process of a UE in a communication systemsupporting a MU-MIMO scheme according to an embodiment of the presentdisclosure has been described with reference to FIG. 5, and anotherexample of an operating process of a BS in a communication systemsupporting a MU-MIMO scheme according to an embodiment of the presentdisclosure will be described with reference to FIG. 6.

FIG. 6 schematically illustrates another example of an operating processof a BS in a communication system supporting a MU-MIMO scheme accordingto an embodiment of the present disclosure.

Referring to FIG. 6, for example, it will be assumed that an operatingprocess of a BS in FIG. 6 is an operating process of a BS according to across-forwarding process described in FIG. 2. That is, it will beassumed that an operating process of a BS in FIG. 6 is an operatingprocess of a BS according to a cross-forwarding process in a case that aBS uses two Tx antennas, e.g., a Tx antenna#1 and a Tx antenna#2 andprovides a service to two UEs, e.g., a UE#1 and a UE#2.

A BS transmits a signal to a UE#1 corresponding to a preset optimal Txbeam index at a preset timing point T1 and transmits a signal to a UE#2corresponding to a preset optimal Tx beam index at the timing point T1at operation 611. For example, the timing point T1 may be a schedulingtiming point.

The BS receives an optimal Tx beam index from each of the UE#1 and theUE#2 at operation 613. Here, it will be assumed that the UE#1 fed backTxBI2 as an optimal Tx beam index and the UE#2 fed back TxBI1 as anoptimal Tx beam index.

The BS feeds forward the optimal Tx beam index TxBI2 received from theUE#1 to the UE#2 thereby the UE#2 detects a correct effective SINR tofeed back a correct CQI to the BS at operation 615. Further, the BSfeeds forward the optimal Tx beam index TxBI1 received from the UE#2 tothe UE#1 thereby the UE#1 detects a correct effective SINR to feed backa correct CQI to the BS at operation 615.

The BS receives a CQI from each of the UE#1 and the UE#2 at operation617. The CQI received from the UE1 is a CQI that the UE#1 determines byconsidering interference strength for remaining UEs other than the UE#1correctly, and the CQI received from the UE2 is a CQI that the UE#2determines by considering interference strength for remaining UEs otherthan the UE#2 correctly.

Although FIG. 6 illustrates another example of an operating process of aBS in a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure, various changes could be made toFIG. 6. For example, although shown as a series of operations, variousoperations in FIG. 6 could overlap, occur in parallel, occur in adifferent order, or occur multiple times.

Another example of an operating process of a BS in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure has been described with reference to FIG. 6, andanother example of an operating process of a UE in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure will be described with reference to FIG. 7.

FIG. 7 schematically illustrates another example of an operating processof a UE in a communication system supporting a MU-MIMO scheme accordingto an embodiment of the present disclosure.

Referring to FIG. 7, for example, it will be assumed that an operatingprocess of a UE in FIG. 7 is an operating process of a UE according to across-forwarding process described in FIG. 2. That is, it will beassumed that an operating process of a UE in FIG. 7 is an operatingprocess of a UE#1 according to a cross-forwarding process in a case thata BS uses two Tx antennas, e.g., a Tx antenna#1 and a Tx antenna#2 andprovides a service to two UEs, e.g., the UE#1 and a UE#2.

The UE#1 receives a signal from a BS at a preset timing point T1 atoperation 711. The UE#1 performs a beam sweeping process on the signalreceived from the BS to detect an optimal Tx beam pattern index atoperation 713. Here, it will be assumed that the UE#1 detects TxBI2 asan optimal Tx beam pattern index.

The UE#1 feeds back the detected optimal Tx beam pattern index TxBI2 tothe BS at operation 715. The UE#1 receives an optimal Tx beam patternindex transmitted by a remaining UE other than the UE#1, e.g., the UE#2from the BS at operation 717.

The UE#1 detects a correct effective SINR by detecting interferencestrength PI based on the optimal Tx beam pattern index transmitted bythe UE#2 which is received from the BS and determines a correct CQIbased on the correct effective SINR at operation 719.

The UE#1 feeds back the determined CQI to the BS at operation 721.

Although FIG. 7 illustrates another example of an operating process of aUE in a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure, various changes could be made toFIG. 7. For example, although shown as a series of operations, variousoperations in FIG. 7 could overlap, occur in parallel, occur in adifferent order, or occur multiple times.

Another example of an operating process of a UE in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure has been described with reference to FIG. 7, andstill another example of an operating process of a BS in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure will be described with reference to FIG. 8.

FIG. 8 schematically illustrates still another example of an operatingprocess of a BS in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure.

Referring to FIG. 8, for example, it will be assumed that an operatingprocess of a BS in FIG. 8 is an operating process of a BS according to across-forwarding process described in FIG. 3. That is, it will beassumed that an operating process of a BS in FIG. 8 is an operatingprocess of a BS according to a cross-forwarding process in a case that aBS uses four Tx antennas, e.g., a Tx antenna#1, a Tx antenna#2, a Txantenna#3, and a Tx antenna#4, and provides a service to four UEs, e.g.,a UE#1, a UE#2, a UE#3, and a UE#4.

A BS transmits a signal to a UE#1 corresponding to a preset optimal Txbeam index at a preset timing point T1, transmits a signal to a UE#2corresponding to a preset optimal Tx beam index at the timing point T1,transmits a signal to a UE#3 corresponding to a preset optimal Tx beamindex at the timing point T1, and transmits a signal to a UE#4corresponding to a preset optimal Tx beam index at the timing point T1at operation 811. For example, the timing point T1 may be a schedulingtiming point.

The BS receives an optimal Tx beam index from each of the UE#1, theUE#2, the UE#3, and the UE#4 at operation 813. Here, it will be assumedthat the UE#1 fed back TxBI1 as an optimal Tx beam index, the UE#2 fedback TxBI2 as an optimal Tx beam index, the UE#3 fed back TxBI3 as anoptimal Tx beam index, and the UE#4 fed back TxBI4 as an optimal Tx beamindex.

The BS feeds forward the optimal Tx beam index TxBI1 received from theUE#1 to each of the UE#2, the UE#3, and the UE#4 thereby each of theUE#2, the UE#3, and the UE#4 detects a correct effective SINR to feedback a correct CQI to the BS at operation 815.

The BS feeds forward the optimal Tx beam index TxBI2 received from theUE#2 to each of the UE#1, the UE#3, and the UE#4 thereby each of theUE#1, the UE#3, and the UE#4 detects a correct effective SINR to feedback a correct CQI to the BS at operation 815.

The BS feeds forward the optimal Tx beam index TxBI3 received from theUE#3 to each of the UE#1, the UE#2, and the UE#4 thereby each of theUE#1, the UE#2, and the UE#4 detects a correct effective SINR to feedback a correct CQI to the BS at operation 815.

The BS feeds forward the optimal Tx beam index TxBI4 received from theUE#4 to each of the UE#1, the UE#2, and the UE#3 thereby each of theUE#1, the UE#2, and the UE#3 detects a correct effective SINR to feedback a correct CQI to the BS at operation 815.

The BS receives a CQI from each of the UE#1, the UE#2, the UE#3, and theUE#4 at operation 817. The CQI received from the UE1 is a CQI that theUE#1 determines by considering interference strength for remaining UEsother than the UE#1 correctly, the CQI received from the UE2 is a CQIthat the UE#2 determines by considering interference strength forremaining UEs other than the UE#2 correctly, the CQI received from theUE3 is a CQI that the UE#3 determines by considering interferencestrength for remaining UEs other than the UE#3 correctly, and the CQIreceived from the UE4 is a CQI that the UE#4 determines by consideringinterference strength for remaining UEs other than the UE#4 correctly.

Although FIG. 8 illustrates still another example of an operatingprocess of a BS in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure, various changescould be made to FIG. 8. For example, although shown as a series ofoperations, various operations in FIG. 8 could overlap, occur inparallel, occur in a different order, or occur multiple times.

Still another example of an operating process of a BS in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure has been described with reference to FIG. 8, andstill another example of an operating process of a UE in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure will be described with reference to FIG. 9.

FIG. 9 schematically illustrates still another example of an operatingprocess of a UE in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure.

Referring to FIG. 9, for example, it will be assumed that an operatingprocess of a UE in FIG. 9 is an operating process of a UE according to across-forwarding process described in FIG. 3. That is, it will beassumed that an operating process of a UE in FIG. 9 is an operatingprocess of a UE according to a cross-forwarding process in a case that aBS uses four Tx antennas, e.g., a Tx antenna#1, a Tx antenna#2, a Txantenna#3, and a Tx antenna#4, and provides a service to four UEs, e.g.,a UE#1, a UE#2, a UE#3, and a UE#4.

The UE#1 receives a signal from a BS at a preset timing point T1 atoperation 911. The UE#1 performs a beam sweeping process on the signalreceived from the BS to detect an optimal Tx beam pattern index atoperation 913. Here, it will be assumed that the UE#1 detects TxBI1 asan optimal Tx beam pattern index.

The UE#1 feeds back the detected optimal Tx beam pattern index TxBI1 tothe BS at operation 915. The UE#1 receives optimal Tx beam patternindexes transmitted by remaining UEs other than the UE#1, e.g., theUE#2, the UE#3, and the UE#4 from the BS at operation 917.

The UE#1 detects a correct effective SINR by detecting interferencestrength PI based on the optimal Tx beam pattern indexes transmitted bythe UE#2, the UE#3, and the UE#4 which are received from the BS anddetermines a correct CQI based on the correct effective SINR atoperation 919.

The UE#1 feeds back the determined CQI to the BS at operation 921.

Although FIG. 9 illustrates still another example of an operatingprocess of a UE in a communication system supporting a MU-MIMO schemeaccording to an embodiment of the present disclosure, various changescould be made to FIG. 9. For example, although shown as a series ofoperations, various operations in FIG. 9 could overlap, occur inparallel, occur in a different order, or occur multiple times.

Still another example of an operating process of a UE in a communicationsystem supporting a MU-MIMO scheme according to an embodiment of thepresent disclosure has been described with reference to FIG. 9, and aninner structure of a BS in a communication system supporting a MU-MIMOscheme according to an embodiment of the present disclosure will bedescribed with reference to FIG. 10.

FIG. 10 schematically illustrates an inner structure of a BS in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 10, a BS 1000 includes a transmitter 1011, acontroller 1013, a receiver 1015, a storage unit 1017, and an outputunit 1019.

The controller 1013 controls the overall operation of the BS 1000. Moreparticularly, the controller 1013 controls an operation related to anoperation of transmitting and receiving Tx beam information and channelquality information performed in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure. Theoperation related to the operation of transmitting and receiving the Txbeam information and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure has been described with referenceto FIGS. 1 to 9 and a detailed description thereof will be omittedherein.

The transmitter 1011 transmits various signals and various messages toother entities, e.g., a UE, and the like included in the communicationsystem supporting the MU-MIMO scheme under a control of the controller1013. The various signals and various messages transmitted in thetransmitter 1011 have been described with reference to FIGS. 1 to 9 anda detailed description thereof will be omitted herein.

The receiver 1015 receives various signals and various messages fromother entities, e.g., a UE, and the like included in the communicationsystem supporting the MU-MIMO scheme under a control of the controller1013. The various signals and various messages received in the receiver1015 have been described with reference to FIGS. 1 to 9 and a detaileddescription thereof will be omitted herein.

The storage unit 1017 stores various programs, various data, and thelike related to the operation of transmitting and receiving the Tx beaminformation and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure under a control of the controller1013.

The storage unit 1017 stores various signals and various messages whichare received by the receiver 1015 from the other entities.

The output unit 1019 outputs various signals and various messagesrelated to the operation of transmitting and receiving the Tx beaminformation and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure which is performed in the BS 1000under a control of the controller 1013. The various signals and variousmessages output by the output unit 1019 have been described withreference to FIGS. 1 to 9 and a detailed description thereof will beomitted herein.

While the transmitter 1011, the controller 1013, the receiver 1015, thestorage unit 1017, and the output unit 1019 are described in the BS 1000as separate units, it is to be understood that this is merely forconvenience of description. In other words, two or more of thetransmitter 1011, the controller 1013, the receiver 1015, the storageunit 1017, and the output unit 1019 may be incorporated into a singleunit.

The BS 1000 may be implemented with one processor.

An inner structure of a BS in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure hasbeen described with reference to FIG. 10, and an inner structure of a UEin a communication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure will be described with reference toFIG. 11.

FIG. 11 schematically illustrates an inner structure of a UE in acommunication system supporting a MU-MIMO scheme according to anembodiment of the present disclosure.

Referring to FIG. 11, a UE 1100 includes a transmitter 1111, acontroller 1113, a receiver 1115, a storage unit 1117, and an outputunit 1119.

The controller 1113 controls the overall operation of the UE 1100. Moreparticularly, the controller 1113 controls an operation related to anoperation of transmitting and receiving Tx beam information and channelquality information performed in a communication system supporting aMU-MIMO scheme according to an embodiment of the present disclosure. Theoperation related to the operation of transmitting and receiving the Txbeam information and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure has been described with referenceto FIGS. 1 to 9 and a detailed description thereof will be omittedherein.

The transmitter 1111 transmits various signals and various messages toother entities, e.g., a BS and the like included in the communicationsystem supporting the MU-MIMO scheme under a control of the controller1113. The various signals and various messages transmitted in thetransmitter 1111 have been described with reference to FIGS. 1 to 9 anda detailed description thereof will be omitted herein.

The receiver 1115 receives various signals and various messages fromother entities, e.g., a BS and the like included in the communicationsystem supporting the MU-MIMO scheme under a control of the controller1113. The various signals and various messages received in the receiver1115 have been described with reference to FIGS. 1 to 9 and a detaileddescription thereof will be omitted herein.

The storage unit 1117 stores various programs, various data, and thelike related to the operation of transmitting and receiving the Tx beaminformation and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure under a control of the controller1113.

The storage unit 1117 stores various signals and various messages whichare received by the receiver 1115 from the other entities.

The output unit 1119 outputs various signals and various messagesrelated to the operation of transmitting and receiving the Tx beaminformation and the channel quality information performed in thecommunication system supporting the MU-MIMO scheme according to anembodiment of the present disclosure which is performed in the UE 1100under a control of the controller 1113. The various signals and variousmessages output by the output unit 1119 have been described withreference to FIGS. 1 to 9 and a detailed description thereof will beomitted herein.

While the transmitter 1111, the controller 1113, the receiver 1115, thestorage unit 1117, and the output unit 1119 are described in the UE 1100as separate units, it is to be understood that this is merely forconvenience of description. In other words, two or more of thetransmitter 1111, the controller 1113, the receiver 1115, the storageunit 1117, and the output unit 1119 may be incorporated into a singleunit.

The UE 1100 may be implemented with one processor.

As is apparent from the foregoing description, an embodiment of thepresent disclosure enables transmission and reception of Tx beaminformation in a communication system supporting a MU-MIMO scheme.

An embodiment of the present disclosure enables transmission andreception of Tx beam information in a case that a mmWave beamformingscheme is used in a communication system supporting a MU-MIMO scheme.

An embodiment of the present disclosure enables to transmission andreception of channel quality information in a communication systemsupporting a MU-MIMO scheme.

An embodiment of the present disclosure enables to transmission andreception of channel quality information in a case that a mmWave schemeis used in a communication system supporting a MU-MIMO scheme.

An embodiment of the present disclosure enables generation of channelquality information by considering interference strength in a case thata mmWave scheme is used in a communication system supporting a MU-MIMOscheme.

An embodiment of the present disclosure enables generation of channelquality information based on Tx beam information for UEs other than a UEin a communication system supporting a MU-MIMO scheme.

Certain aspects of the present disclosure may also be embodied ascomputer readable code on a non-transitory computer readable recordingmedium. A non-transitory computer readable recording medium is any datastorage device that can store data, which can be thereafter read by acomputer system. Examples of the non-transitory computer readablerecording medium include read only memory (ROM), random access memory(RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storagedevices, and carrier waves (such as data transmission through theInternet). The non-transitory computer readable recording medium canalso be distributed over network coupled computer systems so that thecomputer readable code is stored and executed in a distributed fashion.In addition, functional programs, code, and code segments foraccomplishing the present disclosure can be easily construed byprogrammers skilled in the art to which the present disclosure pertains.

It can be appreciated that a method and apparatus according to anembodiment of the present disclosure may be implemented by hardware,software and/or a combination thereof. The software may be stored in anon-volatile storage, for example, an erasable or re-writable read-onlymemory (ROM), a memory, for example, a random-access memory (RAM), amemory chip, a memory device, or a memory integrated circuit (IC), or anoptically or magnetically recordable non-transitory machine-readable(e.g., computer-readable), storage medium (e.g., a compact disk (CD), aDVD, a magnetic disk, a magnetic tape, and/or the like). A method andapparatus according to an embodiment of the present disclosure may beimplemented by a computer or a mobile terminal that includes acontroller and a memory, and the memory may be an example of anon-transitory machine-readable (e.g., computer-readable), storagemedium suitable to store a program or programs including instructionsfor implementing various embodiments of the present disclosure.

The present disclosure may include a program including code forimplementing the apparatus and method as defined by the appended claims,and a non-transitory machine-readable (e.g., computer-readable), storagemedium storing the program. The program may be electronicallytransferred via any media, such as communication signals, which aretransmitted through wired and/or wireless connections, and the presentdisclosure may include their equivalents.

An apparatus according to an embodiment of the present disclosure mayreceive the program from a program providing device which is connectedto the apparatus via a wire or a wireless and store the program. Theprogram providing device may include a memory for storing instructionswhich instruct to perform a content protect method which has beenalready installed, information necessary for the content protect method,and the like, a communication unit for performing a wired or a wirelesscommunication with a graphic processing device, and a controller fortransmitting a related program to a transmitting/receiving device basedon a request of the graphic processing device or automaticallytransmitting the related program to the transmitting/receiving device.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method of a base station (BS) in a communication system, the method comprising: receiving, from each of terminals, transmission beam (Tx beam) information related to a Tx beam selected by each of the terminals; and transmitting, to each of the terminals, Tx beam information received from each of remaining terminals except for a corresponding terminal among the terminals.
 2. The method of claim 1, further comprising: receiving channel quality information from each of the terminals, wherein the channel quality information is determined by considering a strength of the Tx beam selected by each of the remaining terminals as interference strength in the corresponding terminal.
 3. The method of claim 1, further comprising: receiving channel quality information from each of the terminals, wherein the channel quality information is determined based on an effective signal to interference and noise ratio (SINR) of the corresponding terminal, and wherein the effective SINR is determined by considering a strength of the Tx beam selected by each of the remaining terminals as interference strength in the corresponding terminal.
 4. The method of claim 3, wherein the effective SINR is determined based on the following: $\gamma_{eff} = \frac{P_{S}}{P_{I} + P_{N}}$ where, γ_(eff) denotes the effective SINR, P_(S) denotes signal strength of the corresponding terminal, P_(I) denotes the interference strength, and P_(N) denotes noise strength of the corresponding terminal.
 5. The method of claim 1, wherein the Tx beam information of each of the terminals is received at a timing point identical to a timing point at which the channel quality information is received from each of the terminals or at a timing point different from the timing point at which the channel quality information is received from each of the terminals.
 6. The method of claim 1, wherein the Tx beam information of each of the terminals is received through a message identical to a message through which the channel quality information of each of the terminals is received or through a message different from the message through which the channel quality information of each of the terminals is received.
 7. The method of claim 1, wherein the Tx beam information of each of the terminals is transmitted by a period during which channel status is static.
 8. A base station (BS) in a communication system, the BS comprising: a receiver configured to receive, from each of terminals, transmission beam (Tx beam) information related to a Tx beam selected by each of the terminals; and a transmitter configured to transmit, to each of the terminals, Tx beam information received from each of remaining terminals except for a corresponding terminal among the terminals.
 9. The BS of claim 8, wherein the receiver is configured to receive channel quality information from each of the terminals, wherein the channel quality information is determined by considering a strength of the Tx beam selected by each of the remaining terminals as interference strength in the corresponding terminal.
 10. The BS of claim 8, wherein the receiver is configured to receive channel quality information from each of the terminals, wherein the channel quality information is determined based on an effective signal to interference and noise ratio (SINR) of the corresponding terminal, and wherein the effective SINR is determined by considering a strength of the Tx beam selected by each of the remaining terminals as interference strength in the corresponding terminal.
 11. The BS of claim 10, wherein the effective SINR is determined based on the following: $\gamma_{eff} = \frac{P_{S}}{P_{I} + P_{N}}$ where, γ_(eff) denotes the effective SINR, P_(S) denotes signal strength of the corresponding terminal, P_(I) denotes the interference strength, and P_(N) denotes noise strength of the corresponding terminal.
 12. The BS of claim 8, wherein the Tx beam information of each of the terminals is received at a timing point identical to a timing point at which the channel quality information is received from each of the terminals or at a timing point different from the timing point at which the channel quality information is received from each of the terminals.
 13. The BS of claim 8, wherein the Tx beam information of each of the terminals is received through a message identical to a message through which the channel quality information of each of the terminals is received or through a message different from the message through which the channel quality information of each of the terminals is received.
 14. The BS of claim 8, wherein the Tx beam information of each of the terminals is transmitted by a period during which channel status is static.
 15. A base station (BS) in a communication system, the BS comprising: a receiver configured to receive, from a terminal, transmission beam (Tx beam) information related to a Tx beam selected by the terminal; and a transmitter configured to transmit, to at least one terminal other than the terminal, the Tx beam information.
 16. The BS of claim 15, wherein the receiver is configured to receive channel quality information from the at least one terminal, and wherein the channel quality information is determined by considering strength of the Tx beam selected by the terminal as interference strength in the at least one terminal.
 17. The BS of claim 15, wherein the receiver is configured to receive channel quality information from the at least one terminal, wherein the channel quality information is determined based on an effective signal to interference and noise ratio (SINR) of the at least one terminal, and wherein the effective SINR is determined by considering strength of the Tx beam selected by the terminal as interference strength in the at least one terminal.
 18. The BS of claim 15, wherein the Tx beam information of the terminal is received at a timing point identical to a timing point at which the channel quality information is received from the terminal or at a timing point different from the timing point at which the channel quality information is received from the terminal.
 19. The BS of claim 15, wherein the Tx beam information of the terminal is received through a message identical to a message through which the channel quality information of the terminal is received or through a message different from the message through which the channel quality information of the terminal is received.
 20. The BS of claim 15, wherein the Tx beam information of the terminal is transmitted by a period during which channel status is static. 